1. Field of Invention
The invention relates to a method of processing digital images, and more particularly to a method of processing red eye in digital images.
2. Related Art
Digital image processing technology has found wide application in the market of electronic appliances. When a digital photo is taken, the eyes of people or animals may appear red on the photo. This is due to the fact that in dark environments, human or animal eye pupils are more dilated and form a greater open area. Therefore, a flash for which the light axis is closer to the light axis of the camera objective lens will likely reflect on the back of the eye of the photographed subject toward the objective lens. The back of the eye is usually full of red capillaries, which make the subject's eye appear as a red spot on the photo.
As new generations of cameras are promoted, it can be observed that the distance that separates the flash lamp from the camera objective lens is decreasing. This is due to a current design trend that particularly focuses upon the size and portability features of the camera. With the flash lamp being closer to the camera objective lens, the problem of red eye is even more severe.
Although some more advanced cameras are promoted as having anti-red eye operating modes, the problem of red eye is still common in digital images. In traditional mechanical cameras, red eyes are eliminated by using a pre-flash that forces the eye pupils to contract so as to attenuate the reflection of red light at the subsequent flash. However, this technique has limited results, and is not really able to completely eliminate the appearance of red eyes.
Some of present software products available on the market provide red eye elimination functions in post-processing stages. However, these software products use implemented processing methods that require the user's manual operation to adjust and find the location of the red eye, and subsequently determine its color. Only thereafter is the red eye covered up. As a result, these methods of the prior art usually need several adjustments, and consequently are slower and require substantial intervention from the user. If a substantial number of images have to be processed, the processing efficiency is significantly low.
Software products that automatically eliminate red eyes are also known in the art, and they provide convenient operations that do not need intervention from the user. However, these known software products usually use an oval shape or a pattern close to a visage shape as models to determine the visage area in the skin color area. Then the red eyes are searched within the visage. As a result, the search area is relatively large, the search speed is relatively slow, and the precision is adversely affected.